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Slide shows combined and modified from: AP BIOLOGY Chapter 6 Cell Structure & Function WHAT’S NEW you didn’t learn in BIO I?
NUCLEAR ENVELOPE DOUBLE MEMBRANE is fused in spots forming NUCLEAR PORES NUCLEAR LAMINA- netlike array of protein filaments on nuclear side of envelope that maintains the shape of the nucleus (Play a role in reforming nuclear membrane after cell division, if you inject antibodies to lamina proteins, nucleus can’t reform after mitosis)
ENDOMEMBRANE SYSTEM Regulates protein traffic and performs metabolic functions in the cell Includes: Plasma membrane Nuclear membrane Endoplasmic reticulum Golgi apparatus Vacuoles Lysosomes
INSULIN being released by pancreas cells using exocytosis
Golgi apparatus Cisternae = Flattened membrane sacs (look like stacked pancakes) 2 sides = 2 functions cis = (receives vesicles by fusion) trans = buds off vesicles to send to other places (shipping face)
Animation from: See a Golgi movie
LYSOSOMES (common in animal cells but rare in plant cells) Contain hydrolytic enzymes for intracellular digestion Food (Phagocytosis) Damaged organelles AUTOPHAGY ~ “eating self” See movie
LYSOSOMES: Uncontrolled release of lysosome contents into the cytoplasm can also cause cell death (necrosis) APOPTOSIS (self-destruct mechanism) “cell suicide” Embryonic development Removes damaged cells Immune response Cancer cells and AIDS virus override self-destruct signals
WHITE BLOOD CELLS USE LYSOSOMES TO DIGEST ENGULFED BACTERIA (Phagocytosis)
ANIMAL VACUOLES & VESICLES “transport vehicles” FOOD VACUOLES Phagocytosis/ fuse with lysosomes CONTRACTILE VACUOLES Freshwater organisms pump out excess water
PLANT VACUOLES (Central Vacuole) Surrounded by membrane = TONOPLAST Selectively permeable – controls what goes in & out STORAGE Water Stockpile proteins/inorganic ions Deposit metabolic byproducts Store pigments Store defensive compounds against herbivores
Other cell parts with membranes that are NOT part of the Endomembrane system: – Mitochondria – Plastids – Peroxisomes
MITOCHONDRIA- DOUBLE MEMBRANE Outer membrane Inner membrane (CRISTAE) increases surface area for chemical reactions Intermembrane space= Space between inner membrane & outer membrane MATRIX = Space inside cristae folds contains DNA, enzymes, ribosomes
Chloroplasts – site for photosynthesis in plants DOUBLE MEMBRANE Has own DNA Thylakoids – membrane sacs containing light-capturing pigments Grana – closed compartments of stacked thylakoid membranes Stroma – fluid surrounding thylakoids
PLASTIDS CHLOROPLASTS- contain pigment chlorophyll for photosynthesis CHROMOPLASTS- contain pigments that give fruits and flowers colors AMYLOPLASTS- store starch (amylose) in roots and tubers (colorless)
Who else has a circular chromosome not found within a nucleus?
Endosymbiotic Theory Originally proposed in early 1900’s Idea reintroduced in 1963 by Lynn Margulis Suggests that engulfed prokaryotes shared symbiotic relationship with host cell Advantages for both: ~ one supplies energy ~ other raw materials & protection
ENDOSYMBIOTIC THEORY See a movie about ENDOSYMBIOTIC THEORY
Evidence for Endosymbiotic theory 1. Mitochondria and chloroplasts have circular DNA like bacteria. 2. Mitochondria and chloroplasts have ribosomes whose size and structure resemble bacterial ribosomes. 3. Mitochondria and chloroplasts replicate independently of cell division using binary fission like bacteria. 4. Inner membranes of mitochondria and chloroplasts have a composition similar to bacterial membranes.
PEROXISOMES Other digestive enzyme sacs in both plants and animals NOT part of endomembrane system (proteins come from cytosol) In fat storing seeds (called GLYOXYSOMES) Break down fatty acids → sugars transport to mitochondria for energy In LIVER CELLS Help detoxify alcohol & other poisons PRODUCE HYDROGEN PEROXIDE (also a TOXIN) but have enzyme (CATALASE) to break this down H 2 O 2 → H 2 O + O 2